The present invention relates to a process for the preparation of a solid granular intermediate (commonly known in the field of chocolate production as milk or chocolate crumb) useful in the production of milk chocolate, using a bulk sweetener suitable for diabetics, dentally safe and/or having a reduced caloric content. A bulk sweetener refers to a sweetener that, in a composition, has an effect essentially similar to that of sucrose, i.e. it provides both sweetness and bulk to the composition.
Milk chocolate is produced primarily by two different methods. In the most commonly used method, a base mass is formed of the chocolate raw materials (sweetener, milk powder, cocoa liquor and part of the cocoa butter) by mixing and kneading them into a homogeneous, plastic mass. This base mass is processed further by roller refining, the main purpose of which is to diminish the particle size, thereafter by mechanical heat treatment, i.e. conching prior to or during which the remainder of the cocoa butter and the possible emulsifiers, flavours and intense sweeteners are added. During the conching the final taste of the chocolate is produced and the desired consistency of the mass is achieved. In conventional chocolate manufacture with sucrose as sweetener, according to e.g. Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 20, Verlag Chemie, Weinheim, 1981, pp. 682-686, the temperature during the conching can rise up to 80.degree. C.; in milk chocolate manufacture, however, the conching temperature should not exceed 60.degree. C. (see for instance Lees, R. & Jackson, E. B., Sugar Confectionery and Chocolate Manufacture, Leonard Hill, Glasgow, 1985, p. 137). The conching is followed by tempering (pre-crystallization) and forming into a final chocolate product.
In another method, a solid prefabricate, i.e. crumb, is produced from the sweetener, milk (from which part of the water has been evaporated) or milk powder and water and cocoa liquor or part of the cocoa liquor and part of the fat (milk fat and/or cocoa butter) by heating with simultaneous stirring and removing the water contained in the mass in a vacuum, for instance in a vacuum mixer. The product so obtained, the particle size of which varies within a broad range, is refined by milling to a product with a homogeneous particle size. Also in this process the further treatment steps are in principle the same as with the base mass discussed above, that is, the roller refining and conching, prior to and/or during which the remainder of the cocoa liquor and fat and the possible emulsifiers, flavours and intense sweeteners are added, and finally tempering and forming into the desired chocolate product.
These basic processes and the effect of their different steps on the properties of the final product have been described for instance in Minifie, B. W., Chocolate, Cocoa and Confectionery, 2nd Edition, The AVI Publishing Company, Inc., Westport, Conn., 1982, pp. 107-125, and in Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 20, Verlag Chemie, Weinheim, 1981, pp. 682-686.
The most important advantage achieved with the crumb process is the pleasant taste of chocolate produced by this process, which taste is a result of the so-called non-enzymatic browning and caramelization reaction, i.e. Maillard reaction, which takes place during the production of crumb. Aromas that significantly affect the taste of the final chocolate are formed in this reaction. A condition for the occurrence of this reaction is, according to e.g. the above publication by Lees & Jackson, p. 126, that both milk solids and sucrose are present. An additional advantage achieved with the crumb process is that the crumb serves as a basis having a uniform quality for milk chocolate production and has good shelf life, wherefore it can be stored for long periods.
In the manufacture of chocolates that are suitable for diabetics, are dentally safe and/or have a reduced caloric content, fructose or sugar alcohols, such as lactitol, isomalt, maltitol, mannitol, sorbitol and/or xylitol, are most often used as sweeteners. Sugar alcohols however lack the carbonyl group typical to sugars, wherefore they do not participate in the Maillard reaction.
It is also desirable to develop the pleasant taste typical of conventional sucrose chocolates produced by the crumb method when the bulk sweetener is a sugar alcohol. Naturally, the good storability of crumb is a considerable advantage also in these cases.
The use of sugar alcohols as sweeteners in chocolate has been mentioned for example in Finnish Patent Application 922030 (maltitol, lactitol and hydrogenated isomaltulose mentioned as sugar alcohols for the sweetener), WO published application No. 90/06317 (sweetener lactitol monohydrate), U.S. Pat. No. 5,098,730 (sweetener xylitol), WO published application No. 80/01869 and European Patent 0 317 917. Most of these publications relate to processes in which the base mass for chocolate is produced by mixing and kneading the ingredients.
WO published application No. 80/01869 discloses a modified process for preparing crumb products, and sugar alcohols such as sorbitol or xylitol have been mentioned as possible sugar materials to be used as sweeteners. In this process, separate flows of the raw materials are formed, and one of the flows containing milk products and optionally sugar raw materials, amino acids and reducing sugars is subjected to a temperature of 100-130.degree. C. for performing a Maillard reaction. Subsequently this flow is cooled and, at a temperature of 65-75.degree. C., homogenized with a second flow containing fat components and an emulsifier to form an aqueous emulsion. For obtaining a dry crumb product, said emulsion can be dried in a spray drier. In all, the disclosed process is rather complicated and requires special equipments.
European Patent 0 317 917 relates to chocolate production by the crumb method, employing a sweetener substituting sugar. This publication discloses as examples of such sweeteners sugar alcohols, such as sorbitol, mannitol, maltitol, lactitol, xylitol and Palatinit.RTM., etc., the dentally safe disaccharide Palatinos.RTM., leucrose and polydextrose as well as mixtures thereof. In this publication, the fact that these sweeteners required the use of relatively low conching temperatures (40-50.degree. C.) and hence long conching times, with the resultant tendency of the chocolate mass to absorption of atmospheric moisture and/or release of crystal water with consequent undesirable increase in viscosity, and/or agglomeration of the mass, are mentioned as disadvantages associated previously with the use of said sweeteners. These disadvantages are said to be avoided by the process in accordance with the publication, in which the conching temperature is within the range 55-85.degree. C.
The starting temperature in the production of a crumb is normally within the range 90-100.degree. C. when sucrose is used as the sweetener. European Patent 0 317 917 mentions 50-140.degree. C. as the starting temperature in crumb production. In all examples of this patent, the ingredients of the crumb are first heated to 94.degree. C., i.e. to a temperature typically used with sucrose.
Experiments were carried out by the inventors of the present invention on the suitability of lactitol monohydrate in conventional crumb production, the ingredients of the crumb were first heated to 90-95.degree. C. However, the desired crumb product was not obtained, but during the vacuum step a tough mass was produced instead of a dry granular crumb, and this mass was set when cooled into a product of the type of hard candy, and was totally unfit for use in chocolate production. The desired product was not obtained despite repeated experiments. Furthermore, an attempt was made to prepare a crumb from lactitol dihydrate by the conventional crumb production method. However, an unusable, hard-candy like product was obtained also in this case instead of a crystalline crumb.